The present invention relates to a so-called shaft sliding type optical pickup device.
A related shaft sliding type optical pickup device is disclosed in Japanese Patent Publication No. 6-79383B. In such an optical pickup device; a lens holder holding an objective lens is attached rotatably and slidably to a support shaft mounted on a frame and a driving coil is attached to the lens holder and a member on one of sides of the frame, and a magnet is fixed to a member on the other side opposite to the driving coil in a radial direction. A control current is sent in a proper timing with respect to the driving coil. Consequently, the whole lens holder including the objective lens is controlled and moved in a focusing direction (an axial direction) and a tracking direction (a rotating direction).
In such a related shaft sliding type optical pickup device, a magnet for focusing and a magnet for tracking are required. In the related device described, a single magnet 1 is polarized and magnetized (double-pole magnetized) in the focusing direction (vertical direction) and the tracking direction (transverse direction) as shown in FIG. 5.
On the other hand, a magnetic piece 2 is attached to the lens holder opposite to the magnet 1 as shown in FIG. 6, for example. The magnetic piece 2 is provided in a magnetic circuit using the magnet 1. Thus, a magnetic spring structure is constituted. Consequently, the objective lens is held in each of neutral positions in the focusing direction and the tracking direction.
Such a related device has two kinds of magnets 1, that is, a magnet for focusing and a magnet for tracking. Therefore, driving coils should be provided to face the magnets, respectively. For this reason, a reduction in a size and thickness is impeded. On the other hand, in the case in which two kinds of magnets are shared as a single magnet, the arrangement of the magnetic piece becomes a problem.